Fully variable valve controls which allow to adjust the opening and closing time of the load changing valves of an internal combustion engine to the respective operational requirements, provide a considerable improvement potential with respect to reduction of the fuel consumption and pollutant contents in the exhaust gas. In spark ignition engines, for example, it is possible with the aid of such fully variable valve controls to control the output exclusively by a directed adjustment of the opening and closing times of the intake valves so that the throttle valve losses of conventional throttle valve controls can be prevented and a throttle valve can be completely eliminated.
A device of this kind is disclosed in German patent 30 24 199 C2. In this known electromagnetically operating actuating device an armature plate is rigidly connected to the valve stem whereby oppositely acting springs engage the plate so that the armature plate together with the valve forms a system able to oscillate and having a balanced position that corresponds substantially to a half open position of the valve. On both sides of the armature plate pole surfaces of two solenoids are provided which are arranged such that the contact of the armature plate at a respective one of the solenoids corresponds to the fully open position of the valve, respectively, the closed position of the valve. When the valve is, for example, in the closed position and the armature plate is in contact at the corresponding closing solenoid, the valve will oscillate upon deactivation of the closing solenoid under the force of the spring in the direction to the fully open position in which it is secured by excitation of the opening solenoid and the resulting contact at the armature plate at the pole surface of the solenoid. The known device, however, is relatively complicated because of the use of two solenoids which are to be arranged separate from one another and must be precisely controlled with respect to the correct phase. Furthermore, the valve moves with high velocity into its two end positions which due to the high impact velocities can result in acoustic and service life problems.
It is therefore an object of the invention to embody an electromagnetically operating device for valve actuation according to the aforementioned kind such that a high functional reliability can be realized while at the same time a long service life and minimal energy consumption are achieved.